DESCRIPTION: The major goal of the proposal is to understand the molecular biology and replication strategies of the rotaviruses. The three specific aims (taken from the proposal) are: (1) To understand the protein-protein interactions between the viral capsid proteins and the nonstructural glycoprotein NSP4. The relevant domains will be identified by deletion and mutational analysis. The studies are to provide a structural foundation for the understanding of morphogenesis, particle stability and antigenicity as well as virus binding and entry into cells. The second specific aim is to understand the molecular mechanisms and domains responsible for the different properties associated with the nonstructural glycoprotein NSP4. The third specific aim is to understand the morphogenetic process in which particles bud through the membrane of the endoplasmic reticulum and acquire the outer capsid proteins VP4 and VP7. The sequential steps by which single- shelled particles become enveloped and mature into double-shelled particles by the addition of VP4 and VP7 will be determined.